SIMULATION OF GROUND-PENETRATING RADAR WAVES IN A 2-D SOIL MODEL

We have developed a pseudospectral forward modeling algorithm for grou nd-penetrating radar (GPR) based on an explicit solution of the 2-D lo ssy electromagnetic wave equation. Complex soil structures can be acco mmodated with heterogeneous spatial distributions of both wave velocit y and electrical conductivity. This algorithm uses a Gaussian line sou rce with uniform directivity, and there are conductive buffer regions surrounding the soil model to approximate absorbing boundary condition s. Three soil models are used to illustrate different aspects of radar wave propagation. The first model is lossless with homogeneous layers imbedded in a homogeneous background medium, the second model has the same lossless layers in a lossy background medium, and the third mode l is lossless and uses a nonsaturated water flow simulation to create a complex spatial velocity distribution. Two separate simulations with different source frequencies are presented for each soil model. Resul ts indicate that higher frequency GPR will produce a sharper wavelet a nd can map soil layering structures with high resolution. In a conduct ive soil, however, higher frequencies attenuate more rapidly and the r adar may not detect deeper layers.